input: sensors: add hall sensor for msm8909 SKUE

Hall sensor is a switch. It senses magnetic field change and trigger
interrupts to cpu. Add hall sensor driver to provide the feature to
wake up system by covers with magnet.

Change-Id: I061af02942aea6f75d6c7ba6337b877e945110c6
Signed-off-by: Daqing Chen <chendaqing@codeaurora.org>